We describe herein our recent explorations in the field of isonitrile chemistry. An array of broadly useful coupling methodologies has been developed for the formation of peptidyl and glycopeptidyl amide bonds. We further describe the application of these methods to the syntheses of complex systems, including the cyclic peptide cyclosporine A, constrained peptide systems, and heterocycles. New take on an old classic: Recent explorations in the field of isonitrile chemistry led to the development of an array of broadly useful coupling methods for the formation of peptidyl and glycopeptidyl amide bonds. The methods were applied to the syntheses of complex systems, including the cyclic peptide cyclosporine A, constrained peptide systems, and heterocycles (see scheme; FCMA=formimidate carboxylate mixed anhydride).